Heat exchanger



Uct. 14, 1952 w. AVERY ET AL 2,614,198

HEAT EXCHANGER Filed Nov. 27, 1951 Ilka 1M LUMM Patented Oct. 14, 1952[TED STATES PATENT OFFICE HEAT :EXCHANGER Raymond W. Avery, KingsNorton, Birmingham,

and KennethiJ. Dangerfield, Selly Oak, Biramingham, England, assignorsto The Austin -.-Mtor0ompany Limited,.Bir1ningham, England ApplicationNovember 27, 1951, Serial No.258,32s .In Great-Britain December. 13,1950

*Thisiinvention relatesto heatsexchangers, more 'in end plates,the-whole being enclosed by an envelope which is gas tightandlis;.,furnished with appropriately positioned inlet and outletopenings. The gas to be cooled may pass through thetubes and the air maypass through the envelopeand over-or around the-tubes, or 'said gasmay-passoveror aroundthe tubes and the=air may pass through them.

The present invention has for its object to provide a new or improvedmethod of and means for securing the ends of the tubes in their mountingholes in the end plates in a gas tight manner. v

The method according to the invention consists broadly in employingresistance welding, commonly known as spot welding, to make the jointbetween the metal of the tube end and the surrounding metal of the endplate, such welding being performed by causing a large electric currentto flow from an electrode at one outer side of the end plate and throughthe metal of the tube end and that of the plate to another electrode atthe other inner side of the plate, said current being maintained for asuflicient period to ensure fusion of the parts to be joined.

The electrode at the outer side of the end plate preferably will beprovided with a conical end for engaging in the tube end.

The end of the tube at the outer side of the plate preferably will beflared or flanged and the conical-ended electrode will be accuratelyshaped to fit the end of the tube and conform to the flare 0r flangethereon.

The second electrode at the inner side of the plate preferably will beshaped to straddle the tube, and will be formed with blunt projectionsfor making two local area contacts with the plate on either side of thetube at diametrically opposed points. Said second electrode may beprovided with an insert of insulating material between the portion ofthe electrode which straddles the tube and the tube itself.

The invention will now be further described with reference to theaccompanying drawings, in which:

Fig. 1 is a perspective view of a pair of electrodes.

Fig. 2 is a side elevation, partly in section, of a 1 portion of, eheatexchanger' and -.the pairrcfelectrodes,

Referring totthe .drawings, the pairof .elec- .trodes comprises.anupperelectrode it provided with a conical .end H, and-a second lower.electrode 12. Thelowerelectrode i2 is provided with two extensionporti-o-ns, l 3, which both extend laterally rirom the main body of theelectrode at the pedges ofone-sideface thereof, and also I extendupwardly as two blunt projections 14 having contact facessl5. Betweenthetwo .laterallyprojecting portions {3 is located a'Ueshaped insert Hi ofinsulating material. The two 1 electrodes -may be used in anormallpedestal :type spotwelder.

Reierring particularly to Fig. 2 of the drawings, a portion of one endplate of a heat exchanger in process of construction, is shown at H.Portions of two tubes iii are shown with their end portions 28 spotwelded into the plate IT. A third tube It is in position ready forwelding and holes for the reception of the end portions of further tubesare shown at 2!.

The tube H) has its end portion 22 located in a through hole in theplate I1, and the very extreme end of the tube has been provided with aflare or flange 23.

The first electrode Ill is at the outer side of the plate and ready tobe moved downwardly, as when mounted in a pedestal spot-welding machine,whilst the second electrode is at the inner side of the plate, and byreason of its shape it straddles the tube I9, the contact faces i5 ofthe blunt projections M making two local area contacts with the plate llon either side of the tube it at diametrically opposed positions, theinsulating insert l6 preventing any electrical contact between the tubeand the second electrode.

The conical-ended electrode It has its end II accurately shaped to fitinto the end 22 of the tube I9 and conform to the flare or flange 23thereon when said electrode is lowered into welding contact with thesaid tube, and the flare or flange 23 prevents the tube Ill being pushedthrough or further into the hole in the plate I! by the pressure of theconical electrode, before fusion has taken place.

The welding current in passing from the contact faces of one electrodeto the other is constrained to pass through both the tube end and theplate itself, and. by providing an accurately shaped electrode with aconical spigot portion to fit in the end of the tubes having a shoulderor side face to conform to the flare or flange thereon, and also by theprovision of a second bifur- 3 cated electrode to straddle the tube onthe inner side of the end plate, the making of resistance weldedefiicient gas tight joints between the tube ends and the end plates canbe carried out expeditiously as the assembly is built up tube by tube asillustrated in Fig. 2 of the drawings.

The actual size of the contact areas 15 of the second bifurcatedelectrode would be varied as found necessary to suit the characteristicsof the metal used for the tubes and end plates, and also to suit therelative dimensions of tubes and plates, pitch of tubes, and the like.

Having fully described our invention, what We claim and desire to secureby Letters Patent is:

l. The method of resistance welding a tube to a plate, wherein the tubeis receivable within an opening in the plate and the exterior wall ofthe tube adjacent the end thereof contacts the metal of the plate aroundsaid opening, which comprises supporting the plate at one side thereofat spaced apart points spaced from the wall of the tube, moving anelectrode into engagement with the end of said tube at the other side ofthe plate, and passing a welding current from said electrode through themetal of the tube end and the immediately surrounding metal of the plateto said spaced apart points of support, said current being maintainedfor a sufiicient period to insure fusion of the tube and the plate.

2. The method as set forth in claim 1 wherein said electrode is movedinto annular engagement with the end of said tube.

3. The method as set forth in claim 1 which comprises in addition,flaring the end or the tube, and moving the electrode into annularengagement with the flared end of the tube.

4. Mechanism for resistance welding a tube to a plate, wherein the tubeis receivable within an opening in the plate and the exterior wall ofthe tube adjacent the end thereof contacts the metal of the plate aroundsaid opening, comprising an electrode having spaced apart portionsstraddling the tube, said portions engaging the plate at one sidethereof, a second electrode positioned at the other side of the plateand movable into engagement with the end of said tube, and means forpassing a welding current from the second electrode through the metal ofthe tube end and the immediately surrounding metal of the plate to saidspaced apart portions of the first named electrode.

5. Mechanism as set forth in claim 4 which comprises in addition, aninsulating member positioned between the portions of the first namedelectrode and spaced from the tube.

RAYMOND W. AVERY. KENNETH J. DANGERFIELD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 697,560 Steinmetz Apr. 15, 19022,091,982 Hart Sept. 7, 1937

